Golf ball dimples having circumscribed prismatoids

ABSTRACT

The present invention relates to golf balls, specifically, to a golf ball with multifaceted dimples comprising two discrete geometries including a circular perimeter and a depression or protrusion based on a polyhedral prismatoid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/684,682, filed Nov. 26, 2012, which is a continuation ofU.S. patent application Ser. No. 12/584,595, filed Sep. 9, 2009, theentire disclosure of which is hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to golf balls, specifically, to a golfball with multifaceted dimples comprising two discrete geometries.

BACKGROUND OF THE INVENTION

Golf balls generally include a spherical outer surface with a pluralityof dimples formed thereon. Conventional dimples are circular depressionsthat reduce drag and increase lift. These dimples are formed where adimple wall slopes away from the outer surface of the ball forming thedepression.

Drag is the air resistance that opposes the golf ball's flightdirection. As the ball travels through the air, the air that surroundsthe ball has different velocities and thus, different pressures. The airexerts maximum pressure at a stagnation point on the front of the ball.The air then flows around the surface of the ball with an increasedvelocity and reduced pressure. At some separation point, the airseparates from the surface of the ball and generates a large turbulentflow area behind the ball. This flow area, which is called the wake, haslow pressure. The difference between the high pressure in front of theball and the low pressure behind the ball slows the ball down. This isthe primary source of drag for golf balls.

The dimples on the golf ball cause a thin boundary layer of air adjacentto the ball's outer surface to flow in a turbulent manner. Thus, thethin boundary layer is called a turbulent boundary layer. The turbulenceenergizes the boundary layer and helps move the separation point furtherbackward, so that the layer stays attached further along the ball'souter surface. As a result, there is a reduction in the area of thewake, an increase in the pressure behind the ball, and a substantialreduction in drag. It is the circumference portion of each dimple, wherethe dimple wall drops away from the outer surface of the ball, whichactually creates the turbulence in the boundary layer.

Lift is an upward force on the ball that is created by a difference inpressure between the top of the ball and the bottom of the ball. Thisdifference in pressure is created by a warp in the airflow that resultsfrom the ball's backspin. Due to the backspin, the top of the ball moveswith the airflow, which delays the air separation point to a locationfurther backward. Conversely, the bottom of the ball moves against theairflow, which moves the separation point forward. This asymmetricalseparation creates an arch in the flow pattern that requires the airthat flows over the top of the ball to move faster than the air thatflows along the bottom of the ball. As a result, the air above the ballis at a lower pressure than the air underneath the ball. This pressuredifference results in the overall force, called lift, which is exertedupwardly on the ball. Also, the circumference portion of each dimple isimportant in optimizing this flow phenomenon.

By using dimples to decrease drag and increase lift, almost every golfball manufacturer has increased their golf ball flight distances. Inorder to optimize ball performance, it is desirable to have a largenumber of dimples, thus a large amount of dimple circumference, whichare evenly distributed around the ball. In arranging the dimples, anattempt is made to minimize the space between dimples, because suchspace does not improve aerodynamic performance of the ball. In practicalterms, this usually translates into 300 to 500 circular dimples with aconventional-sized dimple having a diameter that ranges from about 0.120inches to about 0.180 inches.

One approach for maximizing the aerodynamic performance of golf balls issuggested in U.S. Pat. No. 6,162,136 (“the '136 patent), wherein apreferred solution is to minimize the land surface or undimpled surfaceof the ball. The '136 patent also discloses that this minimizationshould be balanced against the durability of the ball. Since as the landsurface decreases, the susceptibility of the ball to premature wear andtear by impacts with the golf club increases.

Based on the significant role that dimples play in golf ball design,manufacturers continually seek to develop novel dimple patterns, sizes,shapes, volumes, cross-sections, etc. Thus, the present inventionprovides a novel dimple shape having unique aesthetic and aerodynamiccharacteristics.

SUMMARY OF THE INVENTION

The present invention is directed to a golf ball with improved dimples.The present invention is also directed to a golf ball with improvedaerodynamic characteristics. These and other embodiments of the presentinvention are realized by a golf ball comprising a spherical outer landsurface and a plurality of dimples formed thereon.

In one embodiment, the present invention is directed to a golf ballhaving recessed dimples on the surface thereof, wherein at least onedimple comprises a first circular perimeter located at the chord plane,a second circular perimeter located below the chord plane, and aprismatoid depression or protrusion having a base with a plurality ofvertices that are in contact with the second circular perimeter.

In another embodiment, the present invention is directed to a golf ballhaving recessed dimples on the surface thereof, wherein at least onedimple comprises a first circular perimeter located at the chord plane,a second circular perimeter located below the chord plane and having thesame diameter as the first circular perimeter, and a prismatoiddepression or protrusion having a base with a plurality of vertices thatare not in contact with the second circular perimeter.

In another embodiment, the present invention is directed to a golf ballhaving recessed dimples on the surface thereof, wherein at least onedimple comprises an upper dimple defined by a circular perimeter locatedat the chord plane and an upper dimple sidewall, wherein the upperdimple sidewall terminates at an intersection with a prismatoiddepression or protrusion.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings which form a part of the specification andare to be read in conjunction therewith and in which like referencenumerals are used to indicate like parts in the various views:

FIG. 1 is a partial surface of a golf ball having an eight-edgedprismatoid depression in each dimple;

FIG. 2 is a partial surface of a golf ball having a three-edgedprismatoid depression in each dimple;

FIG. 3 is a partial surface of a golf ball having a circle ratio of0.25;

FIG. 4 is a partial surface of a golf ball having a circle ratio of0.90;

FIG. 5 is a schematic of the circle ratio of a dimple;

FIG. 6 is a schematic indicating edge angle and depth of the prismatoid;

FIG. 7 is a chart of edge angle versus dimple volume;

FIG. 8 shows a golf ball with multifaceted depressions according to anembodiment of the present invention;

FIG. 9 is an enlarged perspective view illustrating a dimple accordingto an embodiment of the present invention;

FIG. 10A shows a golf ball with multifaceted depressions according to anembodiment of the present invention;

FIG. 10B shows a partial surface of the golf ball shown in FIG. 10A;

FIG. 11 is an enlarged perspective view illustrating a dimple accordingto an embodiment of the present invention;

FIG. 12 shows a golf ball with multifaceted depression according to anembodiment of the present invention;

FIG. 13 is an enlarged perspective view illustrating a dimple accordingto an embodiment of the present invention;

FIG. 14 shows a golf ball with multifaceted depression according to anembodiment of the present invention;

FIG. 15 is an enlarged perspective view illustrating a dimple accordingto an embodiment of the present invention;

FIG. 16 shows a golf ball with multifaceted depression according to anembodiment of the present invention; and

FIG. 17 is an enlarged perspective view illustrating a dimple accordingto an embodiment of the present invention.

DETAILED DESCRIPTION

The invention provides for at least one dimple having multifaceteddepressions which include two distinct geometries.

In one embodiment, a first perimeter is concentric about a second,smaller perimeter which circumscribes a prismatoid depression orprotrusion. Primarily the first and second perimeters are circular andthe depressions or protrusions are based on a polyhedral prismatoid. Ina particular aspect of this embodiment, the ratio of the first andsecond diameters is defined by:

$r_{c} = \frac{D_{S}}{D_{D}}$

wherein:

-   -   r_(c) is the circle ratio,    -   D_(D) is the diameter of the first circular perimeter,    -   D_(S) is the diameter of the second circular perimeter, and    -   the range of values for r_(c) is about 0.25 to about 0.90.

For purposes of the present disclosure, the term “circumscribes” refersto a perimeter being in contact with the vertices of the base of aprismatoid.

In a particular embodiment of the present invention, the prismatoidmaintains a minimum of three and a maximum of twelve edges, and isselected from pyramids, cupolas, and frusta.

Referring now to the Figures, as shown generally in FIG. 1, where likenumbers designate like parts, reference number 10 broadly designates apartial surface of a golf ball 10 having a plurality of dimples 12separated by outer undimpled or land surface 14. In accordance to oneaspect of the present invention as shown in FIG. 1, the dimples 12 areformed as multifaceted depressions, each dimple comprising two discretegeometries; a first depression 16 having a first larger circularperimeter 18, and a second, smaller circular diameter 20 concentricwithin the larger circular perimeter 18 and circumscribing a prismatoiddepression 22.

As shown in FIGS. 1-4 and 8-11, in one embodiment, dimple 12 has a firstcircular perimeter 32 located at the chord plane and a second circularperimeter 34 located below the chord plane and marking the terminationof upper dimple sidewall 36. Circumscribed by second circular perimeter34 is a depression or protrusion 40 based on a polyhedral prismatoidwhose base is normal to the dimple axis. The prismatoid does notintersect the phantom spherical ball surface.

According to one aspect of this embodiment, as shown in FIGS. 1-4, 8 and9, second circular perimeter 34 is concentric within first circularperimeter 32. In FIG. 9, the cross-sectional profile of upper dimplesidewall 36 is defined by a spherical function, but may be defined byany suitable function selected from linear, polynomial, posynomial,trigonometric, hyperbolic, exponential functions, and the like.According to another aspect of this embodiment, as shown in FIGS. 10A,10B and 11, second circular perimeter 34 has the same diameter as firstcircular perimeter 32.

As shown in FIGS. 12 and 13, in another embodiment, dimple 12 has afirst circular perimeter 32 located at the chord plane and a secondcircular perimeter 34, having the same diameter as first circularperimeter 32, located below the chord plane and marking the terminationof upper dimple sidewall 36. Concentric within but not circumscribed bysecond circular perimeter 34 is a depression or protrusion 40 based on apolyhedral prismatoid whose base is normal to the dimple axis. Theprismatoid does not intersect the phantom spherical ball surface.

For purposes of the present disclosure, the first circular perimeter andthe second circular perimeter have the same diameter if their diametersare within 3% of each other to allow for manufacturing variances.

As shown in FIGS. 14-17, in another embodiment, dimple 12 has a circularperimeter 32 located at the chord plane and an upper dimple sidewall 36which terminates at an intersection with a prismatoid depression orprotrusion 40. In FIGS. 15 and 17, the cross-sectional profile ofsidewall 36 is defined by a spherical function, but may be defined byany suitable function selected from linear, polynomial, posynomial,trigonometric, hyperbolic, exponential functions, and the like.

According to one aspect of this embodiment, as shown in FIGS. 14 and 15,the vertices of the base of prismatoid 40 are located at the chord planeand, thus, are in contact with circular perimeter 32. According toanother aspect of this embodiment, as shown in FIGS. 16 and 17, thevertices of the base of prismatoid 40 are located below the chord planeand, thus, are not in contact with circular perimeter 32.

In any of the embodiments disclosed herein, the prismatoid is optionallyfurther defined by an intersecting plane that is parallel or oblique tothe prismatoid base forming a truncated prism or cupola.

To maintain adjustability of dimple parameters, the base of theprismatoid maintains a minimum of three and a maximum of twelve edges(N_(E)):

3<N_(E)<12   Equation 1

An example of a dimple prismatoid having eight (8) edges 24 is shown inFIG. 1, while one having 3 edges 24 is shown in FIG. 2.

To allow for manufacturing and adjustability of the dimple, the shapemust adhere to a particular circle ratio (r_(c)), such that the ratio ofdiameters (D_(D)) and (D_(S)) is:

$\begin{matrix}{r_{c} = \frac{D_{S}}{D_{D}}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

The preferable range of values for r_(c) is:

0.25<r_(c)<0.90   Equation 3

Examples of circle ratios are shown in FIGS. 3 and 4, wherein circleratios of 0.25 and 0.90 are respectively depicted, and a schematic ofthe ratios is illustrated in FIG. 5.

Depending on whether the prismatoid is a depression or protrusion, thevolume is a summation from the initial dimple extent, and to calculatefor the two discrete geometries is generally done using a CAD package toaccurately compute the dimple volume.

The chordal volume of the entire dimple, V_(D) is then:

V _(D) =V _(E) +V _(P)   Equation 4

where V_(E) is the dimple extent volume and V_(P) represents the volumeof the prismatoid.

The dimple volume, V_(D), must be such that each dimple maintains aneffective theoretical edge angle (EA_(X)). The effective theoreticaledge angle is determined by computing the equivalent spherical dimpleedge angle EA with dimple volume V_(D) on a golf ball with a diameter(D_(B)). The dimple diameter (D_(D)) is the weighted average for thespecific pattern.

For a given dimple diameter, the chordal volume has an approximatelylinear relationship to the edge angle of the dimple. For example, anaverage dimple diameter of 0.165 inches, a plot of edge angle versuschordal dimple volume is shown in FIG. 7. It is to be appreciated thatthe edge angle is the sum of the chordal and cap angles. When thechordal angle is zero, the chordal volume is also zero and the edgeangle is equal to the cap angle. Thus, the plot is only valid for edgeangles greater than the cap angle for a given dimple diameter (for FIG.7 the edge angle is 5.64°). The plot shows a linear relationship betweenchordal volume and edge angle, which is instrumental in determining theeffective theoretical edge angle, EA_(X).

The effective theoretical edge angle is determined by first computingthe slope of the line relating chordal volume to dimple edge angle forthe weighted average dimple diameter (D_(D)). This is calculated as theratio of cap volume V_(C) to cap angle A_(C) as seen in equation 5.

$\begin{matrix}{m = \frac{V_{C}}{A_{C}}} & {{Equation}\mspace{14mu} 5}\end{matrix}$

The effective theoretical edge angle EA_(X) is calculated as the ratioof the volume V_(D) to the slope plus the included cap angle, as shownis equation 6.

$\begin{matrix}{{EA}_{X} = {\frac{V_{D}}{m} + A_{C}}} & {{Equation}\mspace{14mu} 6}\end{matrix}$

The dimple is designed such that the effective theoretical edge angleEA_(X) is:

9°<EA_(X)<18°  Equation 7

more preferably:

12°<EA_(X)<16°  Equation 8

When numerical lower limits and numerical upper limits are set forthherein, it is contemplated that any combination of these values may beused.

All patents, publications, test procedures, and other references citedherein, including priority documents, are fully incorporated byreference to the extent such disclosure is not inconsistent with thisinvention and for all jurisdictions in which such incorporation ispermitted.

While the illustrative embodiments of the invention have been describedwith particularity, it will be understood that various othermodifications will be apparent to and can be readily made by those ofordinary skill in the art without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the scope of theclaims appended hereto be limited to the examples and descriptions setforth herein, but rather that the claims be construed as encompassingall of the features of patentable novelty which reside in the presentinvention, including all features which would be treated as equivalentsthereof by those of ordinary skill in the art to which the inventionpertains.

What is claimed is:
 1. A golf ball having recessed dimples on thesurface thereof, wherein at least one dimple comprises a first circularperimeter located at the chord plane, a second circular perimeterlocated below the chord plane, and a prismatoid depression or protrusionhaving a base with a plurality of vertices, wherein the vertices are incontact with the second circular perimeter.
 2. The golf ball of claim 1,wherein the first circular perimeter and the second circular perimeterhave the same diameter.
 3. The golf ball of claim 1, wherein the secondcircular perimeter is concentric within the first circular perimeter. 4.The golf ball of claim 3, wherein the ratio of the first circularperimeter diameter and second circular perimeter diameter is defined by:$r_{c} = \frac{D_{S}}{D_{D}}$ wherein: r_(c) is the circle ratio, D_(D)is the diameter of the first circular perimeter, D_(S) is the diameterof the second circular perimeter, and the range of values for r_(c) isfrom about 0.25 to about 0.90.
 5. The golf ball of claim 1, wherein theprismatoid is further defined by an intersecting plane that is parallelto the prismatoid base.
 6. The golf ball of claim 1, wherein theprismatoid is further defined by an intersecting plane that is obliqueto the prismatoid base.
 7. A golf ball having recessed dimples on thesurface thereof, wherein at least one dimple comprises a first circularperimeter located at the chord plane, a second circular perimeterlocated below the chord plane and having the same diameter as the firstcircular perimeter, and a prismatoid depression or protrusion having abase with a plurality of vertices, wherein the vertices are not incontact with the second circular perimeter.
 8. The golf ball of claim 7,wherein the prismatoid is further defined by an intersecting plane thatis parallel to the prismatoid base.
 9. The golf ball of claim 7, whereinthe prismatoid is further defined by an intersecting plane that isoblique to the prismatoid base.
 10. A golf ball having recessed dimpleson the surface thereof, wherein at least one dimple comprises: an upperdimple defined by a circular perimeter located at the chord plane and anupper dimple sidewall, wherein the upper dimple sidewall terminates atan intersection with a prismatoid depression or protrusion.
 11. The golfball of claim 10, wherein the prismatoid comprises a base and aplurality of vertices, and wherein the vertices are in contact with thecircular perimeter.
 12. The golf ball of claim 10, wherein theprismatoid comprises a base and a plurality of vertices, and wherein thevertices are not in contact with the circular perimeter.
 13. The golfball of claim 10, wherein the prismatoid is further defined by anintersecting plane that is parallel to the prismatoid base.
 14. The golfball of claim 10, wherein the prismatoid is further defined by anintersecting plane that is oblique to the prismatoid base.